High Idle control

[Legacy777]

Somone asked this on the USMB
http://www.ultimatesubaru.net/usmb/foru ... adid=12256

Basically he does emergency response stuff, and has a lot of electrical load. He would like some way to bump the idle up so his alternator is outputting more amperage. I told him the simple solution was to put a penny or something between the throttle stop and throttle linkage, but he wants something that's a little more instant and safe to do from the side of the road.

vrg3, any ideas on an electrical way to do this....tie into the IAC valve or some other sensor to force a high idle.....coolant temp maybe....but you're going to start screwing with a/f ratios then.

[vrg3]

I'm gonna post a response to that thread, but a brief response here: what actually occurs to me first is to leave the ECU alone and instead do one of two things: use the cruise control actuator somehow, or add in an extra solenoid in parallel with the IAC valve.

[Legacy777]

yeah I thought about some extra cabling and the cruise actuator is there.....if you could rig up something to use a separate vacuum controller to the cruise actuator.....that'd be pretty cool....not sure how involved that would be though.

[ciper]

The high idle is controlled by the temperature spring.

How about turning the AC on?

[vrg3]

The high idle is controlled by the temperature spring.

Huh? Can you explain what you mean?

[ciper]

When the coolant is cold the spring gets smaller and lets more air in.

[Legacy777]

yeah there is a little valve that closes when temp increases. Unfortunately I don't have any pics.

[vrg3]

Oh, you guys are talking about inside the IAC valve. Yeah.

About the cruise actuator, I was thinking of something really simple:

When you flip the switch on, it supplies +12v to the motor and valves, and grounds the vent valve (the safety valve is always grounded). It also runs the motor for a prespecified amount of time determined by a simple one-shot timer.

I don't know how well the cruise actuator holds vacuum -- if it's not so great at it this won't work. But that's the idea anyway.

[ciper]

If it is duty cycle driven why not just make a timer curcuit to send 10/50 12 volt pulses? Like the torquemada that was never made?

[vrg3]

If what is duty cycle driven? The cruise control system isn't pulse width modulated.

What is the torquemada that was never made?

[ciper]

Torquemada was a box that let you adjust between 0-100% pulse. You connected it to your center diff (clutch based or VTD) in order to create a DCCD for automatics.

I didnt realize how the cruise in a legacy worked. Ive seen a different setup, where it had sort of an IAC valve on it. Vacuum would drop as the opening enlarged.

[vrg3]

Oh, cool... I was gonna make a box like that if I ever owned another Subaru automatic.

Our cruise control system has a motor that just acts like a plunger in a syringe, and two valves to vent vacuum rapidly.

[Legacy777]

Oh, cool... I was gonna make a box like that if I ever owned another Subaru automatic.

Our cruise control system has a motor that just acts like a plunger in a syringe, and two valves to vent vacuum rapidly.

if you made a box like that.....you'd have nabisco peeps all over it

[ciper]

Once I get the Fuel Cut Defender ready for the market Im either going to make this or a digital A/F Boost gauge combo.

I want to create my own line of low cost/high qaulity electronics. This site was the inspiration.

[vrg3]

I'd make one for myself but I don't think I'd want to deal with the hassle and liabilities of selling them. I would just give people all the information necessary to build their own easily.

I'm all about the DIY electronics. People pay waaaay too much money for most automotive electronics.